libite/README.md

-lite | Frog DNA, basically
===========================
[![Travis Status][]][Travis]


Table of Contents
-----------------

* [Introduction](#introduction)
* [Using -lite](#using--lite)
* [Helper Macros](#helper-macros)
* [Generic Functions](#generic-functions)
* [OpenBSD Functions](#openbsd-functions)
* [Build & Install](#origin--references)
* [TODO](#todo)


Introduction
------------

Libite is a lightweight library of *frog DNA*.  It can be used to fill
the gaps in any dinosaur project.  It holds useful functions and macros
developed by both [Finit][1] and the [OpenBSD][2] project.  Most notably
the string functions: [strlcpy(3)][3], [strlcat(3)][3] and the highly
useful *BSD [sys/queue.h][4] and [sys/tree.h][7] API's.

Libite is the frog DNA missing in GNU libc.  However, -lite does not aim
to become another [GLIB][5]!  One noticeable gap in GLIBC is the missing
`_SAFE` macros in the BSD `sys/queue.h` API — highly recommended
when traversing lists to delete/free nodes.

The code is open sourced under a mix of the [MIT/X11 license][MIT], the
[ISC license][ISC] used by OpenBSD, and [BSD licenses][BSD], all of them
are extremely liberal and can be used freely in proprietary software if
needed.

For an introduction to why Libite happened, and how you can use it, see
[this blog post][6].


Using -lite
-----------

Libite is by default installed as a library and a set of include files.
To prevent clashing with include files of the same name `-lite` employs
an include file namespace `lite/`, which is strongly recommended to use
in your applications:

    #include <lite/lite.h>
    #include <lite/conio.h>
    #include <lite/queue.h>
    #include <lite/tree.h>

The output from the `pkg-config` tool holds no surprises in this regard:

    $ pkg-config --libs --static --cflags libite
    -I/usr/local/include -L/usr/local/lib -lite

The prefix path `/usr/local/` shown here is only the default.  Use the
`configure` script to select a different prefix when installing libite.

For GNU autotools based projects, use the following in `configure.ac`:

    # Check for required libraries
    PKG_CHECK_MODULES([lite], [libite >= 1.5.0])

and in your `Makefile.am`:

    proggy_CFLAGS = $(lite_CFLAGS)
    proggy_LDADD  = $(lite_LIBS)


Important Note
--------------

When using functions like `mkpath()`, `makepath()`, and `makefifo()`,
make sure your `umask()` is correct so you do not accidentally create
files and directories accessible to other users than intended.


Helper Macros
-------------

- `atonum(str)`

  Convert string to natural number, works for 32-bit non-negative
  integers.  Returns -1 on error.  (Uses `strtonum()` internally.)

- `blkdev(dev)`

  Create block device

- `chardev(dev)`

  Create character device

- `erase(path)`

  Erase file/directory with `remove()`.  Errors on `stderr`

- `makedir(path)`

  Create directory, like `mkdir()`.  Errors on `stderr`

- `makefifo(path)`

  Create a FIFO, like `mkfifo()`.  Errors on `stderr`

- `min(a,b)`/`max(a,b)`

  These macros take care to avoid double evaluation.

- `touch(path)`

  Create a file, or update mtime.  Errors on `stderr`

- `S_ISEXEC(mode_t m)`

  Mysteriously missing from GLIBC

- `ISCLR(word,bit)`

  Is bit in (integer) word cleared?

- `ISSET(word,bit)`

  Is bit in (integer) word set?

- `ISOTHER(word,bit)`

  Are any other bits, except bit, in (integer) word set?

- `SETBIT(word,bit)`

  Set bit in (integer) word.

- `CLRBIT(word,bit)`

  Clear bit in (integer) word.

- `NELEMS(array)`

  Returns the number of elements in an array.  From the great book, The
  Practice of Programming, by Kernighan and Pike.

- `UNUSED(var)`

  Shorter and more readable version of `var __attribute__ ((unused))`


Generic Functions
-----------------

- `chomp(str)`

  Perl like chomp function, chop off last char if newline.

- `copyfile(src, dst, len, symlink)`

  Like the shell `cp(1)` and `dd(1),` can also create symlinks.

- `dir(dir, ext, filter, list, strip)`

  Wrapper for `scandir()` with optional filter.  Returns a list of
  names: files and directories that must be freed after use.  See
  the unit test for an example, or take a look at `glob(3)`, it's
  probably what you want anyway.

- `fcopyfile(src, dst)`

  Like `copyfile()` but uses already open `FILE *` pointers.  Copies
  from current file positions to current file positions until EOF.

- `fexist(file)`

  Check for the existence of a file, returns True(1) or False(0).

- `fisdir(path)`

  Check for the existence of a directory, returns True(1) or False(0).

- `fmode(file)`

  Returns the `mode_t` bits of a file or directory.

- `fsendfile(src, dst, len)`

  Copy data between file streams, very similar to `fcopyfile()`, but
  `dst` is allowed to be `NULL` to be able to read and discard `len`
  bytes from `src`.

- `ifconfig(ifname, addr, mask, up)`

  Basic ifconfig like operations on an interface.  Only supports IPv4
  addresses.  Note that mask is not CIDR notation.

- `lfopen(file, sep)`, `lfclose(lf)`

  LITE file API for parsing UNIX style configuration files like
  `/etc/protocols` and `/etc/services`.

- `lftok(lf)`

  Read tokens, delimited by `sep`, from file opened with `lfopen()`.

- `lfgetkey(lf, key)`

  Find `key` in file opened with `lfopen()`, return value/argument.

- `lfgetint(lf, key)`

  Wrapper for `lfgetkey()`, returns positive integer value to `key`,
  or `-1` if `key` is not found.

- `fgetint(file, sep, key)`

  Wrapper for `lfopen()`, `lfgetint()`, and `lfclose()`.  Useful for
  when only reading a single `key` from a file.

- `makepath(dir)`

  Create all components of the specified directory.

- `mkpath(dir, mode)`

  Like `makepath()`, but also takes a `mode_t` permission mode argument.

- `movefile(src, dst)`

  Like `copyfile()`, but renames `src` to `dst`, or recreates symlink
  with the `dst` name.  On successful operation the source is removed
  and the function returns POSIX OK (0).

- `pidfile(name)`

  Create a daemon PID file using either the `name` as a full path, if
  `name` starts with `/`, or in `_PATH_VARRUN` using `name` as the
  basename of the application.  If `name` is `NULL`, then `__progname`
  is used as the basename.  The resulting file name is available to the
  user as a read-only pointer:

        extern char *__pidfile_name;

  Use this function to create a PID file for your daemon when it is
  ready to receive signals.  A client application may poll for the
  existence of this file, so make sure to have your signal handlers
  properly setup before calling this function.

  The PID file is removed when the program exits, using an `atexit()`
  handler.  However, depending on how the program terminates the file
  may still exist even though the program is no longer running.

  Calling this function multiple times updates the mtime of the file.
  Only one `atexit()` handler is created, regardless of the amount of
  times the function is called.  If the file is removed, subsequent
  calls to this function will recreate the file.
  
  See below for a link to OpenBSD man page.

- `pidfile_read(pidfile)`

  Read PID from pid file created by `pidfile()`.

- `pidfile_signal(pidfile, signal)`

  Send signal to PID found in pid file created by `pidfile()`.

- `progress(percent, max_width)`

  Simple ASCII progress bar with a spinner.  Start it with `percent=0`
  and set the `max_width=chars` to indicate width of the progress bar.
  Called multiple times with the same percentage value cause spinner to
  spin.

- `rsync(src, dst, delete, *filter())`

  Very simple `rsync()` to copy files files and directories
  recursively.

- `tempfile()`

  Secure replacement for `tmpfile()`.  Creates an invisible temporary
  file in `/tmp` that is removed when the returned `FILE` pointer is
  closed.
  
  **Note:** Requires Linux v3.11, or later, will fall back to the old
    and unsafe `tmpfile()` on older systems.

- `tree(path, show_perms)`

  Very simple `/bin/tree` replacement.  Draw ASCII tree of `path`, with
  optional listing of file and directory permissions if `show_perms` is
  set.  The `path` argument should be a directory.


GNU Functions
-------------

The following are useful GNU functions, that do not exist on *BSD, and
some other platforms.

- `strdupa(str)`

  http://man7.org/linux/man-pages/man3/strdupa.3.html

- `strndupa(str)`

  http://man7.org/linux/man-pages/man3/strndupa.3.html

- `strnlen(str, lim)`

  http://man7.org/linux/man-pages/man3/strnlen.3.html


OpenBSD/NetBSD/FreeBSD Functions
--------------------------------

The following are popular functions and highly useful macros from the
*BSD world of UNIX that are sadly missing on Linux.

- `fparseln(fp, *len, *lineno, delim, flags)`

  http://man.openbsd.org/OpenBSD-current/man3/fparseln.3

- `pidfile(basename)`

  http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/pidfile.3

  **Note:** the version of `pidfile()` in -lite has been extended to
  handle it being called multiple times, i.e. to not create multiple
  `atexit()` handlers, and also to export a few internal paths:

	- `__pidfile_path`: prefix path, default `_PATH_VARRUN`.  Notice the
	  trailing slash requirement if you want to override it!
	- `__pidfile_name`: full path to PID file , similar to `__progname`.
	  See previous section for details.

- `reallocarray(ptr, nmemb, size)`

  http://man.openbsd.org/OpenBSD-current/man3/reallocarray.3

- `strlcpy(dst, src, len)`

  http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/strlcpy.3

- `strlcat(dst, src, len)`

  http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/strlcat.3

- `strtonum()`

  http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/strtonum.3

- `sys/queue.h` API

  http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/LIST_EMPTY.3

- `sys/tree.h` API

  Niels Provos' famous splay and red-black tree implementation.

  http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/SPLAY_FOREACH.3


Build & Install
---------------

This library was initially built for and developed on GNU/Linux systems
as a light weight utility library, these days NetBSD should also work.
Libite (LITE) employs the de facto standard GNU configure and build
system:

    ./configure
    make -j5
    sudo make install-strip
    sudo ldconfig

**Note:** When checking code from GitHub, use <kbd>./autogen.sh</kbd> to
generate a `configure` script.  It is a generated file and otherwise only
included in released tarballs.


TODO
----

- Improve documentation, possibly use kdoc or gdoc2 to generate docs from API.
- Continuously, update OpenBSD functions/macros.

[1]: https://github.com/troglobit/finit
[2]: http://www.openbsd.org/
[3]: http://www.openbsd.org/cgi-bin/man.cgi?query=strlcpy
[4]: http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/LIST_EMPTY.3
[5]: https://developer.gnome.org/glib/
[6]: http://troglobit.com/blog/2015/07/02/howto-using-lite-with-a-git-based-application/
[7]: http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/SPLAY_FOREACH.3
[MIT]: https://en.wikipedia.org/wiki/MIT_License
[ISC]: https://en.wikipedia.org/wiki/ISC_license
[BSD]: https://en.wikipedia.org/wiki/BSD_licenses
[Travis]: https://travis-ci.org/troglobit/libite
[Travis Status]: https://travis-ci.org/troglobit/libite.png?branch=master

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